from machine import Pin, Timer
import time

# -------- Settings --------
GREEN_TIME = 5000
YELLOW_TIME = 2000
RED_TIME = 5000
DEBOUNCE_MS = 200

# -------- Pins --------
green_led = Pin(25, Pin.OUT)
yellow_led = Pin(26, Pin.OUT)
red_led = Pin(27, Pin.OUT)

button = Pin(4, Pin.IN, Pin.PULL_UP)

# -------- State --------
last_press = 0
pedestrian_request = False

# traffic states
GREEN = 0
YELLOW = 1
RED = 2

current_state = GREEN

# timer
traffic_timer = Timer(0)

# -------- LED Control --------
def set_lights(state):
    green_led.off()
    yellow_led.off()
    red_led.off()

    if state == GREEN:
        green_led.on()
    elif state == YELLOW:
        yellow_led.on()
    else:
        red_led.on()

# -------- Interrupt --------
def button_pressed(pin):
    global last_press, pedestrian_request
    now = time.ticks_ms()
    if time.ticks_diff(now, last_press) >= DEBOUNCE_MS:
        pedestrian_request = True
        print("Pedestrian requested")
        last_press = now

# -------- Timer Callback --------
def change_traffic(timer):
    global current_state, pedestrian_request
    if pedestrian_request and current_state != RED:
        current_state = RED
        set_lights(RED)
        pedestrian_request = False
        print("Crossing")
        traffic_timer.init(period=RED_TIME, mode=Timer.ONE_SHOT, callback=change_traffic)
        return

    if current_state == GREEN:
        current_state = YELLOW
        set_lights(YELLOW)
        traffic_timer.init(period=YELLOW_TIME, mode=Timer.ONE_SHOT, callback=change_traffic)
    elif current_state == YELLOW:
        current_state = RED
        set_lights(RED)
        traffic_timer.init(period=RED_TIME, mode=Timer.ONE_SHOT, callback=change_traffic)
    elif current_state == RED:
        current_state = GREEN
        set_lights(GREEN)
        traffic_timer.init(period=GREEN_TIME, mode=Timer.ONE_SHOT, callback=change_traffic)

# attach interrupt
button.irq(trigger=Pin.IRQ_FALLING, handler=button_pressed)

# -------- Start System --------
print("Traffic Light System Started")
set_lights(GREEN)
traffic_timer.init(period=GREEN_TIME, mode=Timer.ONE_SHOT, callback=change_traffic)

# -------- Main Loop --------
while True:

    # main loop stays free
    time.sleep_ms(10)